The invention relates to a compact hydraulic aggregate which possesses a housing forming a reservoir for a pressure fluid, which comprises a housing bottom, a housing cover and a housing middle part therebetween in the form of a profiled tube, an electric motor located in the housing whose in stator laminated core is held by the housing middle part and which can be connected to an electricity network via a connection box on the housing cover, and a pump located within the housing in the region of the housing bottom and capable of being driven by the electric motor.
Such a compact hydraulic aggregate is known, for example, from DE 35 13 472 C2. In such a hydraulic aggregate, the housing may also be regarded as the housing of the electric motor. The rotor and stator of the electric motor are more or less deeply immersed into the pressure fluid, depending on how much oil has been introduced into the reservoir and how much pressure fluid is specifically received by the hydraulic user or users which are supplied with pressure fluid by the pump. The heat generated by the electric motor and the heat introduced into the reservoir by the pressure fluid is released to the environment via the housing. In some circumstances, the pressure fluid, when flowing back from the hydraulic user, additionally passes through an oil cooler in order to reduce the input of heat into the reservoir. This oil cooler may be directly affixed to the hydraulic aggregate.
The housing middle part of the known hydraulic aggregate is of circular cross-sectional form internally in the region of the stator laminated core of the electric motor. An exchange of pressure fluid between the spaces in front of the two end faces of the stator laminated core is evidently to take place via channels in the stator laminated core.
In the known compact hydraulic aggregate, the internal diameter of the housing middle part is determined by the external diameter of the stator laminated core, so that, for a given stock of pressure fluid, a particular height of the hydraulic aggregate results, whereby the placement of the hydraulic aggregate adjacent to a machine is sometimes prevented. In addition, the flow cross section is small because of the channels of the stator laminated core accepting the coils. In some circumstances, additional longitudinal channels have to be made in the stator laminated core, which results in an electric motor of special design.
It is an object of the present invention further to develop a compact hydraulic aggregate having the features of the introductory-mentioned paragraph in such a manner that, especially if additional members are built on, it can be produced cost-effectively. In addition, a low structural length is to be possible for a given pressure fluid storage volume.
This object is achieved, according to the invention, in that a compact hydraulic aggregate having the introductory-mentioned features is additionally equipped with features wherein holding webs make the external diameter of the stator laminated core and the internal diameter of the housing middle part independent of one another, as it were, and the housing middle part can be formed independently of the size of the electric motor to suit the desired storage volume of the pressure fluid and in the interests of a small structural length of the hydraulic aggregate. There is a great deal of free space between the holding webs for the completely unobstructed exchange of pressure fluid between the two spaces in front of the end faces of the stator laminated core. The heat generated in the electric motor is guided outward via the holding webs and released to the environment via the outer surface of the housing middle part.
Particularly preferably, the housing middle part has the external shape of a polygon, in particular a regular polygon. In this arrangement, a partial surface between two corners should lie diametrally opposite a further partial surface, so that the housing middle part can be well clamped for machining. In addition, a component which is externally angular can be stacked better than a circular component. The holding webs advantageously each extend at the center of an external partial surface of the housing middle part lying between two corners, so that the accumulation of material in the corners does not become too great.
An embodiment of the invention is also particularly preferred wherein the housing middle part comprises a further axially extending internal web between two holding webs for the stator laminated core of the electric motor, which further web is broader in the circumferential direction of the housing middle part than the holding webs and serves to secure a monitoring member located externally on the housing. For example, threaded holes can be drilled in the further web to permit the attachment of an oil level display glass.
This further holding web is also preferably located at the center of an external partial surface of the polygonal housing middle part, so that a level installation surface for the monitoring member is provided externally.
As has already been indicated, the compact hydraulic aggregate can additionally be equipped with an oil cooler which is disposed in the region of the housing bottom, for example even below the housing bottom. Preferably, the fan wheel of this oil cooler is driven by a further electric motor, so that no shaft need be guided out from the housing forming the reservoir. According to a feature of the invention provision is now made, in an advantageous manner, for the supply cable for the electric motor to be guided in an axially extending cable duct of the housing middle part to the housing cover, and especially into the connection box there. The supply cable is thus largely protected against damage. In particular, the cable duct also extends within the housing bottom and the housing cover, so that the cable is not visible at all from outside.
A temperature sensor, which can be used, for example, for switching an existing oil cooler on and off or, if no oil cooler is present, switches off the electric motor driving the pump is advantageously disposed in accordance with other features of the invention wherein the electrical connection line of the temperature sensor thus extends freely neither inside nor outside the housing.